Process for making polyester/platelet particle compositions displaying improved dispersion

ABSTRACT

The present invention relates to polyester-platelet particle composite comprising; at least one polyester having dispersed therein a platelet particle dispersion comprising about 0.01 to about 25 weight percent platelet particles and at least one water dissipatible polymer in a concentration which is at least about 1 part water dissipatible polymer to 1 part said polyester wherein said platelet particles primarily comprise individual platelet particles and tactoids. The composites of the present invention are prepared by dispersing at least one clay material in a water dissipatible polymer to form a platelet particle dispersion; introducing said platelet particle dispersion to a polyester and extrusion mixing said dispersion and polyester.

RELATED APPLICATIONS

This application claims the benefit of provisional application U.S.Serial No. 60/053,576 filed on Jul. 21, 1997.

BACKGROUND OF THE INVENTION

Polyesters such as poly(ethylene terephthalate) (PET) are widely used inbottles and containers which are used for carbonated beverages, fruitjuices, and certain foods. Useful polyesters have high inherentviscosities (I.V.) which allow the polyester to be formed into a parisonand subsequently molded into a container. Because of the limited barrierproperties with regard to oxygen, carbon dioxide and the like, PETcontainers are not generally used for products requiring long shelflife. For example, oxygen transmission into PET bottles that containbeer, wine and certain food products cause these products to spoil.

The preparation of polymer/clay nanocomposites containing for example,nylon-6 and alkyl ammoniun treated montmorillonite have been disclosed.However, most prior attempts used polyarnides due to their hydrogenbonding character and corresponding synergistic interaction with thenegatively charged clay. The application of this technology topolyesters, particularly to improve barrier, has been limited due to theinability to achieve the required level of dispersion of the clayparticles.

U.S. Pat. No. 4,889,885 discloses the polymerization of various vinylmonomers such as methyl methacrylate and isoprene in the presence ofsodium montmorillonite. Example 11 describes the polycondensation ofdimethyl terephthalate and ethylene glycol in the presence of 33 weightpercent of a montmorillonite clay in water (for 6.2 final weight percentof clay in the polyester resin). However, the nanocomposite displayedonly marginal improvement in barrier due to insufficient separation.Moreover, to achieve desirable molecular weights, the method usedunacceptably long synthesis times to compensate for reduced condensationrates resulting from the high composite viscosity at low shear thatoccurs upon addition of the clay. In addition, the long exposure timesto high-temperature during the polyester synthesis resulted in poornanocomposite color.

WO 93/04117 and WO 93/04118 disclose the blending of up to 60 weightpercent of intercalated clay materials with a wide range of polymersincluding polyamides, polyesters, polurethanes, polycarbonates,polyolefins, vinyl polymers, thermosetting resins and the like. Althoughthe use of polyesters are disclosed as useful polymers and an example ofa PET/Quat-Clay nanocomposite is providing in WO 93/04118, compositionsprepared as described exhibit insufficient clay dispersion resulting inaesthetically poor composites. In addition, this method of preparationdoes not lead to improved barrier due to lack of separation.

U.S. Pat. Nos. 5,552,469 and 5,578,672 describes the preparation ofintercalates derived from certain clays and water-soluble polymers suchas polylvinyl pyrrolidone, polyvinyl alcohol, and polyacrylic acid. Thespecification describes a wide range of thermoplastic resins includingpolyesters and rubbers that can be used in blends with theseintercalates. The disadvantages of this method are (1) poor thermalstability of the intercalant resin at PET processing temperaturescausing extensive color and reactivity with the polyester resin, (2)poor compatibility with the polyester resin, (3) and insufficientcontribution to barrier due to incomplete separation. The inability tocontribute to barrier would not be predicted based on the disappearanceof the d(001) montmorillonte X-ray defraction pattern as observed inFIG. 5 of U.S. Pat. No. 5,578,672.

JP Kokai patent no. 9-176461 discloses polyester bottles wherein thepolyester contains swellable laminar silicate. WO 97/31057 disclosespolymer composite having dispersed therein inorganic material such asclay which is separated with an inorganic intercalant. WO 97/31973discloses a producing a composite material by mixing a potassium ionomerin which ethylene methacrylate copolymer is either partially orcompletely neutralized with an organic polymer. However, the foregoingreferences produce materials comprising very large tactoids and littleif any dispersion of individual platelet particles. Nor do any of thereferences disclose nanocomposite compositions having other specificproperties such as melt strength and viscoity and high I.V.

Thus there remains a need in the art for a process capable ofintroducing substantially separated platelet particles to polyesters toproduce nanocomposites having improved barrier and good thermalstability.

DESCRIPTION OF THE FIGURES

FIG. 1 is an X-ray plot for a polyester-platelet particle compositecontaining 2 weight % untreated sodium montmorillonite.

FIG. 2 is an X-ray plot for a polyester-platelet particle compositecontaining 2 weight % sodium montmorillonite treated with 4 weight % AQ55.

FIG. 3 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % untreated sodiummontmorillonite.

FIG. 4 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % sodium montmorillonite treatedwith 4 weight % AQ 55.

FIG. 5 is a transmission electron micrograph at 30,000× of PETpolyester-platelet particle composite containing 2 weight % untreatedsodium montmorillonite.

FIG. 6 is a transmission electron micrograph at 30,000× of PETpolyester-platelet particle composite containing 2 weight % sodiummontmorillonite treated with 4 weight % AQ-55.

FIG. 7 is a transmission electron micrograph at 1,000,000× of PETpolyester-platelet particle composite containing 2 weight % untreatedsodium montmorillonite.

FIG. 8 is a transmission electron micrograph at 1,000,000× of PETpolyester-platelet particle composite containing 2 weight % sodiummontmorillonite treated with 4 weight % AQ-55.

FIG. 9 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % sodium montmorillonite treatedwith 30 weight % PVP.

FIG. 10 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % [sodium montmorillonite treatedwith 30 weight % PVP] treated with 4 weight % AQ 55.

FIG. 11 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % untreated Claytone APA.

FIG. 12 is an optical micrograph at 20× of PET polyester-plateletparticle composite containing 2 weight % Claytone treated with 4 weight% AQ 55.

FIG. 13 is a transmission electron micrograph at 100,000× of PETpolyester-platelet particle composite containing 2 weight % untreatedClaytone APA.

FIG. 14 is a transmission electron micrograph at 100,000× of PETpolyester-platelet particle composite containing 2 weight % Claytonetreated with 2 weight % AQ-55.

FIG. 15 is a transmission electron micrograph at 100,000+ of PETpolyester-platelet particle composite containing 2 weight % Claytonetreated with 4 weight % AQ-55.

FIG. 16 is a transmission electron micrograph at 100,000× of PETpolyester-platelet particle composite containing 2 weight % Claytonetreated with 8 weight % AQ-55.

FIG. 17 is a transmission electron micrograph at 100,000× of PETpolyester-platelet particle composite containing 2 weight % Claytonetreated with 14 weight % AQ-55.

FIG. 18 is a viscosity versus shear rate plot comparing a plateletparticle-polyester composite of the present invention and unmodifiedPET.

DESCRIPTION OF THE INVENTION

This invention relates to a process for preparing polyester compositematerials composed of polyester resin and platelet particles uniformlydispersed therein that exhibit improved gas barrier properties; thecomposite materials so produced, and products produced from saidcomposite.

More particularly, the present invention relates to dispersionscomprising water-dispersable polymers and dispersed therein plateletparticles derived from various clay materials which may be untreated ormetal intercalated, organically modified through cation ion exchange;intercalated with other high molecular weight pretreatment compounds.The dispersion effectiveness of the water-dispersible polymers arestrongly influenced by the presence of anionic sulfo-salt modification;a feature that would not be expected to be beneficial, based on thenegative charged characteristic of the clay surface.

More specifically, this invention relates to a process comprising thesteps of dispersing at least one clay material in a water dispersiblepolymer to form a clay dispersion; introducing said dispersion to apolyester and extrusion mixing said dispersion and polyester to form aplatelet particle-polyester composite composition which is primarilycomprised of platelet particles and tactoids. Composite compositionsproduced according to the present invention display a gas permeabilitywhich is at least 5% lower than that of unmodified polyester.

In a typical procedure, the desired clay is added to water to form asuspension. Enough water is added to make a stirrable solution,preferably greater than about 20:1, and more preferably from about 25:1to about 35:1 parts water to parts clay by weight. Larger amounts ofwater may be used, but generally are not preferred because most of thewater should generally be driven off prior to compounding. Ifmodification of the clay surface (e.g., use of a quaternary ammoniumsalt) is desired, this can be done either prior to or subsequent to theaddition of the water. The water dispersible polymer is added to theclay/water suspension. Generally, the water dispersible polymer is addedin solution form. The amount of water dispersible polymer necessary toachieve optimum platelet particle separation can be confirmed X-raydefraction and confirmed by Transmission Electron Microscopy. Thereduction in oxygen permeability achieved will depend on the clay and inparticular, the clay surface modification. Improvements in plateletparticle separation in the polyester are seen at concentrations of waterdissipatible polymer as low as about 1:1 water dissipatiblepolymer:platelet particle. Amounts of water dissipatible polymer whichare greater than about 20:1 may not be preferred in some applicationsdue to the large amount of water dissipatible polymer which results inthe base polyester. Preferably, desirable ranges include those fromabout 1:1 to about 15:1 and more preferably from about 1:1 to about 10:1parts water dissipatible polymer to platelet particle as determined byASTM D5630-94. Typically the solution is thoroughly mixed using a devicesuch as a low-shear Waring blender or a high-shear Turrax mixer.Typically, the solution is stirred to form a slurry, which can beaccomplished in times of about 5 minutes.

The platelet particle slurry can be coated onto polyester pellets ordried and then introduced onto the pellets or into the polyester in thedesired amount via a variety of methods. For example, the aqueous slurrycan be added directly to polyester pellets and heat applied to removethe water leaving the platelet particle/water soluble polymer coated onthe external surface of the polyester pellets. In practice, the removalof water could be accomplished using a batch device such as a heatedSigma blade mixer or a continuous process such as an extruder to driveoff the water leaving the platelet particle coated pellet. Similarly acontinuous process can be employed whereby the platelet particle slurryis sprayed on heated pellets as the pellets are passed over a vibratingshaker deck. Using either the batch or continuous processes previouslycited, platelet particles can be introduced in the polyester resin toachieve the desired property enhancement or can be incorporated at aconcentration the can be diluted in a subsequent operation to thedesired target concentration. An alternative method to remove water fromthe aqueous clay/water-dispersable polymer slurry would be to employspray drying; the spray-dried, polymer-expanded clay can be addeddirectly to polyester using a conventional melt blending process oradded directly to a melt fabrication device such as an injection moldingmachine or extrusion line.

The process of the present invention is highly beneficial in that highmolecular weight polyesters may be prepared in a conventional manner andthen be extrusion blended with expanded platelet particles. FIG. 18 is aplot comparing viscosity versus shear rate for a plateletparticle-polyester composite of the present invention and unmodifiedPET.

For example, in a specific embodiment of the process, a smectite-typeclay is added to water in an amount of approximately 20 grams water pergram silicate. About 30 g of the water dispersible polymer, AQ55 isadded to about 70 g water. The solution is then mixed for 5 minutesusing a Turrax high-speed mixer. The slurry is then charged to a Sigmablade mixer or vented extruder with polyester pellets (1680 g) at 100°C. and the water is driven off to provide polyester pellets coated withAQ/clay. The coated pellets are then either premixed by melt-blending(e.g., twin-screw extruder) or can be directly added to a subsequentfabrication machine (e.g., film extruder or bottle pre-form moldingmachine).

Other methods common to polyester synthesis (e.g., use of solid-statingto increase molecular weight) can be utilized. In addition, additivesknown to those skilled in polyester formulation, especially to affectresin/filler interfaces (e.g., pH adjustment and use of surfactants),can also be added during the preparation of the slurry.

Alternatively, the AQ/clay/water slurry could be spray-dried and addedto the polyester during a subsequent melt-blending operation.

Dispersion Aid

Suitable dispersion aids include water dissipatable polymers. The waterdissipatable polymers of the present invention are, for the most part,water-dissipatable (or water dispersible) because they formelectrostatically-stabilized colloids when mixed with water. The colloidparticle size varies with the polymer composition but has been shown bylight diffraction studies and transmission electron microscopy (on freshfilms) to be mostly 200-800 Å in diameter. The aqueous colloiddispersions exhibit a minimum precipitation of solid material with time,in the temperature range of 0.1-99.9° C. because the relationshipbetween the particle densities and viscosities (very similar to those ofwater when concentrations are less than 30 weight percent) are such thatthermal energy expressed as Brownian motion is sufficient to keep theparticles suspended in water.

The water-dispersible polymers have an inherent viscosity of at leastabout 0.1 dL/g, preferably about 0.28-about 0.38 dL/g, when determinedat 25° C. using 0.25 g polymer per 100 ml of a solvent consisting of 60parts by weight phenol and 40 parts by weight tetrachloro-ethane.

Preferably the water dissipatable polymers include sulfonate-containing,water-dispersible, linear polymers comprising polyesters, includingpolyester-amides, consisting of repeating, alternating residues of (1)one or more dicarboxylic acids and (2) one or more diols or acombination of one or more diols and one or more diamines where, in thepreceding definition, the mole percentages are based on 100 mole percentdicarboxylic acid residues and 100 mole percent diol or diol and diamineresidues. Alternatively, the polymers may include residues of monomershaving mixed functionality such as hydroxycarboxylic acids,aminocarboxylic acids and/or aminoalkanols.

Generally the water-dissipatable polyesters and polyesteramides derivedfrom monomer components which include dicarboxylic acid,hydroxycarboxylic acid, aminocarboxylic acid, aminoalcohol, glycol,diamine or combinations of such monomer components wherein at least apart of the total of all such monomer components is poly(ethyleneglycol), and at least a part of said total is one or more of saidmonomer components substituted with one or more sulfonate metal saltgroups.

The residues of dicarboxylic acid component (1) may be derived from oneor more dicarboxylic acids or their ester-forming derivatives such asdialkyl esters, bis(hydroxyalkyl)esters, acid chlorides or, in somecases, anhydrides. The sulfonate group may be an alkali metal sulfonicsalt such as lithium, potassium or, preferably, sodium sulfonate groups,or an ammonium or substituted ammonium sulfonate.

The preferred water-dispersible polymers have an inherent viscosity ofabout 0.28 to 0.38 dL/g and are comprised of:

(i) diacid monomer residues comprising about 75 to 84 mole percentisophthalic acid monomer residues and about 16 to 25 mole percent5-sodiosulfoisophthalic acid monomer residues; and

(ii) diol monomer residues comprising about 45 to 60 mole percentdiethylene glycol monomer residues and about 40 to 55 mole percentethylene glycol, 1,4-cyclohexanedimethanol monomer residues or mixturesthereof.

Specific embodiments of these water-dispersible polymers are availablefrom Eastman Chemical Company, (EASTMAN AQ 29S Polymer, EASTMAN 38SPolymer and EASTMAN 55S Polymer) and in the form of aqueous dispersions(EASTMAN AQ 29D Polymer, EASTMAN 38D Polymer and EASTMAN 55D Polymer).These polyesters have been shown to disperse in water due to thepresence of 5-sodiosulfoisophthalic acid residues.

Preferably, the water dispersible polyester above contains somepoly(ethylene glycol) to aid in its water dispersibility. When somepoly(ethylene glycol) is used, the content of the sulfomonomer can belower, which aids in flexibility of formulating the polyester.

The water dispersibility of the polyester is related to the weightpercent of poly(ethylene glycol) and mole percent of sulfomonomer.Therefore, if the content of either is relatively low, the other shouldbe relatively high to maintain adequate dispersibility.

The poly(ethylene glycol) need not be present in the initial reactioncharge, because poly(ethylene glycol) may form in situ fromdecomposition products and be incorporated into the polyester chain. Itis well known, for example, that diethylene glycol is formed in situ insuch reactions.

In the preferred form of the present invention, the polyester containsrepeating units of a poly(ethylene glycol) of the formula H--(OCH₂--CH₂)_(n) --OH wherein n is an integer of 2 to 500. The value of n ispreferably from between about 2 to about 20. The values of n and themole percent of poly(ethylene glycol) in the polyester, if used, areadjusted such that the mole percent of poly(ethylene glycol) within thestated range is inversely proportional to the quantity of n within thestated ranges. Thus, when the mole percent is high, the value of n islow. On the other hand, if the mole percent is low, the value of n ishigh. It is apparent, therefore, that the weight percent (product ofmole percent and molecular weight) of the poly(ethylene glycol) is animportant consideration because the water dissipatability of thecopolyester decreases as the weight percent poly(ethylene glycol) in thecopolyester decreases. For example, if the weight of poly(ethyleneglycol) is too low, the water dissipatability of the copolyester may beinadequate. Furthermore, the weight percent of poly(ethylene glycol) ispreferably adjusted such that it is inversely proportional to the molepercent of the difunctional sulfomonomer because the waterdissipatability of the copolyester is a function of both the molepercent sulfomonomer and the weight percent polyethylene glycol.

Examples of suitable poly(ethylene glycols) include relatively highmolecular weight polyethylene glycols, some of which are availablecommercially under the designation CARBOWAX, a product of Union Carbide.Diethylene glycol is also especially suitable.

Other useful glycols for preparing copolyesters include aliphatic,alicyclic and aralkyl glycols. Examples of these glycols includeethylene glycol; propylene glycol; 1,3-propanediol;2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3-propanediol;1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2,4-trimethyl-1,6-hexanediol; thiodiethanol.1,2-cyclohexanedimethanol, 1,3-cyclohexandimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; andp-xylylenediol.

The dicarboxylic acid component of the polyesters are preferablyselected from aliphatic dicarboxylic acids, alicyclic dicarboxylicacids, aromatic dicarboxylic acids, or mixtures of two or more of theseacids. Examples of such dicarboxylic acids, include succinic; glutaric;adipic; azelaic; sebacic; 1,4-cyclohexanedicarboxylic; phthalic;terephthalic and isophthalic acid. Terephthalic acid and isophthalicacid are preferred as the carboxylic acid component of the polyester.

It should be understood that use of the corresponding acid anhydrides,esters, and acid chlorides of these acids is included in the term"dicarboxylic acid."

The difunctional sulfomonomer component of the polyester mayadvantageously be a dicarboxylic acid or an ester thereof containing ametal sulfonate group, a glycol containing a metal sulfonate group or ahydroxy acid containing a metal sulfonate group. The metal ion of thesulfonate salt may be Na+, Li+, K+ and the like. When a monovalentalkali metal ion is used, the resulting polyesters are less readilydissipated by cold water and more readily dissipated by hot water. Whena divalent or a trivalent metal ion is used the resulting polyesters arenot ordinarily easily dissipated by cold water but are more readilydissipated in hot water. It is possible to prepare the polyester using,for example, a sodium sulfonate salt and latex and by ion-exchangereplace this ion with a different ion, and thus alter thecharacteristics of the polymer. The difunctional monomer component mayalso be referred to the difunctional sulfomonomer and is furtherdescribed herein below.

Advantageous difunctional sulfomonomer components are those wherein thesulfonate salt group is attached to an aromatic acid nucleus such asbenzene, naphthalene, diphenyl, oxydiphenyl, sulfonyldiphenyl ormethylenediphenyl nucleus. Preferred results are obtained through theuse of sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalicacid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and their esters.

Particularly superior results are achieved when the difunctionalsulfomonomer component is 5-sodiosulfoisophthalic acid or its esters,and the glycol is a mixture of ethylene glycol or1,4-cyclohexanedimethanol with diethylene glycol.

A particularly preferred water dissipatable polymer is composed of 80mole parts of isophthalic acid, 10 mole parts of adipic acid, 10 moleparts of 5-sodiosulfoisophthalate, 20 mole parts of ethylene glycol and80 mole parts diethylene glycol.

Platelet Particles

The compositions of the present invention comprise between about 0.01and about 25 wt %, preferably between 0.5 and 25 wt %, more preferablybetween 0.5 and 15 wt % and most preferably between 0.5 and 10 wt % ofcertain platelet particles derived from organic and inorganic claymaterials. The amount of platelet particles is determined by measuringthe amount of ash of the polyester-platelet compositions when treated inaccordance with ASTM D5630-94, which is incorporated herein byreference.

The platelet particles of the present invention have a thickness of lessthan about 2 nm and a diameter in the range of about 10 to about 1000nm. For the purposes of this invention measurements refer only to theplatelet particle and not any dispersing aids or pretreatment compoundswhich might be used. Suitable platelet particles are derived from claymaterials which are free flowing powders having a cation exchangecapacity between about 0.3 and about 3 meq/g and preferably betweenabout 0.8 and about 1.5 meq/g. Examples of suitable clay materialsinclude mica-type layered phyllosilicates, including clays, smectiteclays, sodium montmorillonite, sodium hectorite, bentonites, nontronite,beidelite, volonsloite, saponite, sauconite, magadiite, kenyaite,synthetic sodium hecotorites, and the like. Clays of this nature areavailable from various companies including Southern Clay Products andNanocor, Inc. Generally the clay materials are a dense agglomeration ofplatelet particles which are closely stacked together like cards.

Other non-clay materials having the above described ion exchangecapacity and size, such as chlalcogens may also be used as the source ofplatelet particles under the present invention. These materials areknown in the art and need not be described in detail here.

The prior art has defined the degree of separation of the plateletparticles based on peak intensity and basal spacing, or lack thereof, asdetermined by X-ray analyses of polymer-platelet composites. However, inpolyester composites X-ray analysis alone does not accurately predictthe dispersion of the platelet particles in the polyester nor theresultant barrier improvement. TEM images of polyester-plateletcomposites show that platelet particles which are incorporated into atleast one polyester exist in a variety of forms, including, but notlimited to invdividual platelets (the exfoliated state), disorderedagglomerates of platelets, well ordered or stacked aggregates ofplatelets (tactoids) and aggregates of tactoids. X-ray analysis onlyprovides information related to the well ordered aggregates, which areonly a small portion of the platelet particles which are present.

Without being bound by any particular theory, it is believed that thedegree of improved barrier depends upon the aspect ratio of theresulting particle platelets and aggregates, the degree to which theyare dispersed or uniformly distributed and the degree to which they areordered perpendicular to the flux of the permeant. To obtain theimprovements in gas permeability and the enhanced melt viscositydisclosed in the present invention it is necessary that the plateletparticles be dispersed in the polyester such that the majority,preferably at least about 75% and perhaps as much as at least about 90or more of the platelet particles have a thickness in the shortestdimension of less than about 20 nm and preferably less than about 10 mnas estimated from TEM images representative of the bulk of thecomposite. Polyester-platelet composites containing more individualplatelets and fewer aggregates, ordered or disordered are mostpreferred. Significant levels of incomplete dispersion (i.e., thepresence of large agglomerates and tactoids greater than about 20 nm)not only lead to an exponential reduction in the potential barrierimprovements attributable to the platelet particles, but also can leadto deleterious affects to other properties inherent to polyester resinssuch as strength, toughness, and heat resistance.

Dispersions containing a high level of individual platelet particleshave not been previously disclosed. Previous patents and applicationshave claimed to produce polyesters containing intercalated or exfoliatedplatelet particles, as indicated by large basal spacings or the lack ofa detectable basal spacing by X-ray, however, the results could not bereproduced. With the exception of WO 93/04118 (which does not possesssuitable I.V.), the polyester/platelet compositions of the prior art arebelieved to be dispersions of aggregates with large thickness, typicallygreater than about 20 nm. While the aggregates were well spaced, veryfew individual platelets and tactoids or particles with thicknesses lessthan about 20 nm could be found. Without achieving a good dispersion andsmall particle size improved barrier and visual properties cannot beachieved.

Improvements in gas barrier also increase as the amount of plateletparticles in the polyester increases. While amounts of plateletparticles as low as 0.01% provide improved barrier (especially when welldispersed and ordered), compositions having at least about 0.5 wt % ofthe platelet particles are preferred because they display the desiredimprovements in gas permeability.

Generally, it is desirable to treat the selected clay material tofacilitate separation of the agglomerates of platelet particles toindividual platelet particles and small tactoids. Separating theplatelet particles prior to incorporation into the polyester alsoimproves the polyester/platelet interface. Any treatment that achievesthe above goals may be used. Examples of useful treatments includeintercalation with water soluble or water insoluble polymers, organicreagents or monomers, silane compounds, metals or organometallics,organic cations to effect cation exchange, and their combinations.

Treatment of the clay can be accomplished prior to addition of waterdispersible polymer to the clay material, during the dispersion of theclay with the water soluble polymer or during a subsequent melt blendingor melt fabrication step.

Examples of useful pretreatment with polymers and oligomers includethose disclosed in U.S. Pat Nos. 5,552,469 and 5,578,672, incorporatedherein by reference. Examples of useful polymers for intercalating theplatelet particles include polyvinyl pyrrolidone, polyvinyl alcohol,polyethylene glycol, polytetrahydrofuran, polystyrene, polycaprolactone,certain water dispersable polyesters, Nylon-6 and the like.

Examples of useful pretreatment with organic reagents and monomersinclude those disclosed in EP 780,340 A1, incorporated herein byreference. Examples of useful organic reagents and monomers forintercalating the platelet particles include dodecylpyrrolidone,caprolactone, aprolactam, ethylene carbonate, ethylene glycol,bishydroxyethyl terephthalate, dimethyl terephthalate, and the like ormixtures thereof.

Examples of useful pretreatment with silane compounds include thosetreatements disclosed in WO 93/11190, incorporated herein by reference.Examples of useful silane compounds includes(3-glycidoxypropyl)trimethoxysilane, 2-methoxy(polyethyleneoxy)propylheptamethyl trisiloxane, octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride and the like.

Numerous methods to modify layered particles with organic cations areknown, and any of these may be used in the process of this invention.One embodiment of this invention is the modification of a layeredparticle with an organic cation by the process of dispersing a layeredparticle material in hot water, most preferably from 50 to 80° C.,adding an organic cation salt or combinations of organic cation salts(neat or dissolved in water or alcohol) with agitation, then blendingfor a period of time sufficient for the organic cations to exchange mostof the metal cations present in the galleries between the layers of theclay material. Then, the organically modified layered particle materialis isolated by methods known in the art including, but not limited to,filtration, centrifugation, spray drying, and their combinations. It isdesirable to use a sufficient amojnt of the organic cation salt topermit exchange of most of the metal cations in the galleries of thelayered particle for organic cations; therefore, at least about 1equivalent of organic cation salt is used and up to about 3 equivalentsof organic cation salt can be used. It is preferred that about 1.1 to 2equivalents of organic cation salt be used, more preferable about 1.1 to1.5 equivalents. It is desirable, but not required, to remove most ofthe metal cation salt and most of the excess organic cation salt bywashing and other techniques known in the art. The particle size of theorganoclay is reduced in size by methods known in the art, including,but not limited to, grinding, pulverizing, hammer milling, jet milling,and their combinations. It is preferred that the average particle sizebe reduced to less than 100 micron in diameter, more preferably lessthan 50 micron in diameter, and most preferably less than 20 micron indiameter.

Useful organic cation salts for the process of this invention can berepresented as follows: ##STR1## Wherein M represents either nitrogen orphosphourous; X⁻ represents an anion selected from the group consistingof halogen, hydroxide, or acetate anions, preferably chloride andbromide; R₁, R₂, R₃ and R₄ are independently selected from organic andoligomeric ligands or may be hydrogen. Examples of useful organicligands include, but are not limited to, linear or branched alkyl groupshaving 1 to 22 carbon atoms, aralkyl groups which are benzyl andsubstituted benzyl moieties including fused ring moieties having linearchains or branches of 1 to 22 carbon atoms in the alkyl portion of thestructure, aryl groups such as phenyl and substituted phenyl includingfused ring aromatic substituents, beta, gamma unsaturated groups havingsix or less carbon atoms, and alkyleneoxide groups having 2 to 6 carbonatoms. Examples of useful oligomeric ligands include, but are notlimited to, poly(alkylene oxide), polystyrene, polyacrylate,polycaprolactone, and the like.

Examples of useful organic cations include, but are not limited to,alkyl ammonium ions, such as dodecyl ammonium, octadecyl ammonium,bis(2-hydroxyethyl)octadecyl methyl ammonium, octadecyl benzyl dimethylammonium, tetramethyl ammonium, and the like or mixtures thereof, andalkyl phosphonium ions such as tetrabutyl phosphonium, trioctyloctadecyl phosphonium, tetraoctyl phosphonium, octadecyl triphenylphosphonium, and the like or mixtures thereof. Illustrative examples ofsuitable organo-clays include those available under the trade nameClaytone® and Cloisite® from Southern Clay Products.

It should be appreciated that on a total composition basis dispersingaids and/or pretreatment compounds which are used may account forsignificant amount of the total composition, in some cases up to about30 weight %. While it is preferred to use as little dispersingaid/pretreatment compounds as possible, the amounts of dispersing aidsand/or pretreatment compounds may be as much as about 8 times the amountof the platelet particles.

Polyesters

The polyester component of the compound of the present invention ispresent in amounts between about 99.99 wt % to about 75 wt %, preferablybetween 99.5 and about 75 wt %, more preferably 99.5 to about 85 wt %and most preferably between 99.5 and about 90 wt %. Suitable polyestersinclude at least one dibasic acid and at least one glycol. The primarydibasic acids are terephthalic, isophthalic, naphthalenedicarboxylic,1,4-cyclohexanedicarboxylic acid and the like. The various isomers ofnaphthalenedicarboxylic acid or mixtures of isomers may be used but the1,4-, 1,5-, 2,6-, and 2,7-isomers are preferred. The1,4-cyclohexanedicarboxylic acid may be in the form of cis, trans, orcis/trans mixtures. In addition to the acid forms, the lower alkylesters or acid chlorides may be also be used.

The dicarboxylic acid component of the polyester may optionally bemodified with up to about 50 mole percent of one or more differentdicarboxylic acids. Such additional dicarboxylic acids includedicarboxylic acids having from 6 to about 40 carbon atoms, and morepreferably dicarboxylic acids selected from aromatic dicarboxylic acidspreferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acidspreferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylicacids preferably having 8 to 12 carbon atoms. Examples of suitabledicarboxylic acids include phthalic acid, isophthalic acid,naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinicacid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and thelike. Polyesters may be prepared from two or more of the abovedicarboxylic acids.

Typical glycols used in the polyester include those containing from twoto about ten carbon atoms. Preferred glycols include ethylene glycol,propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol,diethylene glycol and the like. The glycol component may optionally bemodified with up to about 50 mole percent, preferably up to about 25mole % and more preferably up to about 15 mole % of one or moredifferent diols. Such additional diols include cycloaliphatic diolspreferably having 6 to 20 carbon atoms or aliphatic diols preferablyhaving 3 to 20 carbon atoms. Examples of such diols include: diethyleneglycol, triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol,butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol,3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4),2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3),2,2-diethylpropane-diol-(1,3), hexanediol-(1,3),1,4-di-(2-hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,2,2-bis-(3-hydroxyethoxyphenyl)-propane,2,2-bis-(4-hydroxypropoxyphenyl)-propane and the like. Polyesters may beprepared from two or more of the above diols.

Small amounts of multifunctional polyols such as trimethylolpropane,pentaerydiritol, glycerol and the like may be used if desired. Whenusing 1,4-cyclohexanedimethanol, it may be the cis, trans or cis/transmixtures.

The resin may also contain small amounts of trifinctional ortetrafunctional comonomers to provide controlled branching in thepolymers. Such comonomers include trimellitic anhydride,trimethylolpropane, pyromellitic dianhydride, pentaerythritol,trimellitic acid, trimellitic acid, pyromellitic acid and otherpolyester forming polyacids or polyols generally known in the art.

Although not required, additives normally used in polyesters may be usedif desired. Such additives include colorants, pigments, carbon black,glass fibers, impact modifiers, antioxidants, stabilizers, flameretardants, reheat aids, acetaldehyde reducing compounds and the like.

The polyester/disperesed platelet compositions should be crystallizableto an extent that is sufficient to prevent sticking during solidstating.

EXAMPLES Comparative 1 (Na-Montmorillonite Without AQ 55)

PET pellets [(9921 Eastman Chemical Company) were placed in a convectionoven at 110° C. until processed (minimum of twelve hours, maximum oftwenty-four hours) by extrusion compounding. The pellets weretumble-blended with Sodium Montmorillonite from Southern Clay Products(2 w %) then extruded using a Micro-18 twin screw compounding extruder,with a high shear/mixing screw, obtaining pellets as the product. Therun conditions were set at 240° C. for the first screw heating zone and280° C. for heating zones two through eight. The RPM of the extrusionscrew was maintained at 200 plus or minus five rpm. The product feedscrew was set to maintain 2.5 kg/hr. The molten strand was quenched inchilled water and chopped immediately thereafter. The pellets were driedat 100° C. over night in a force air drier and extruded into film. Thecompounded pellets were analyzed by X-ray, Optical Miscroscopy at 20×,and Transmission Electron Miscroscopy at 30,000 and 1,000,000×. Nosignificant peak was visible in the X-ray plot (FIG. 1), which,according to prior patents, indicates exfoliation. However, the opticalmicrograph (FIG. 3) and TEMs (FIG. 5 and 7) clearly show few individualplatelet particles and several large agglomerates containing many poorlyspaced platelet particles. On both a macroscale and nanoscale untreatedsodium montmorillonite displayed poor dispersion in PET. Clearly, X-raydata alone is insufficient to confirm the desired separation of plateletparticles. The oxygen permeability of the film showed no substantialimprovement, confirming the poor dispersion of platelet particles.

Example 1 Na-Montmorillonite With AQ 55

An AQ 55 dispersion was made, such that, every 100 grams of dispersioncontained thirty grams AQ 55 total solids by weight and seventy gramsMillipore water by weight, giving a total solids in the dispersion equalto 30% by weight. A "slurry" of Millipore water and clay was made byadding forty grams (total silicate by weight) of Sodium Montmorilloniteto 600 grams of Millipore water. The clay was dispersed with athree-blade mixer until the clay appeared to be fully wet. At this pointan Ultra-Turrax 25 with the S25n-25F dispersing tool was used to inputhigh shear mixing (18,000 rpm) for two minutes. After high shear mixingof the slurry, 266.7 grams of AQ55 (Eastman Chemical Company) 30%dispersion was added to the slurry. Using the Ultra-Turrax 25, thewater/AQ 55/clay dispersion was sheared for an additional five minutes.PET pellets (9921, Eastman Chemical Company), 1680 grams, were placed ina Sigma Blade Mixer that had been preheated to a minimum of 85° C. Thewater/AQ55/clay slurry was poured over the pellets and the newdispersion was mixed in the Sigma Blade mixer until the water from thedispersion had evaporated. A flow of a minimum of twenty cubic feet perhour of heated nitrogen was released over the pellets to help evacuatethe water.

Coated pellets were placed in a convection oven at 110° C. untilprocessed (minimum of twelve hours, maximum of twenty-four hours) byextrusion compounding. The coated pellets were extruded using aLeistritz Micro-18 twin screw co-rotating compounding extruder, with ahigh shear/mixing screw, obtaining pellets as the product. The runconditions were set at 240° C. for the first screw heating zone and 280°C. for heating zones two through eight. The RPM of the extrusion screwwas maintained at 200 plus or minus five rpm. The product feed screw wasset to maintain 2.5 kg/hr. The molten strand was quenched in chilledwater and chopped immediately thereafter. The pellets were dried at 100°C. over night in a force air drier and extruded into film. Thecompounded pellets were analyzed by X-ray (FIG. 2), Optical Miscroscopyat 20×, (FIG. 4) and Transmission Electron Microscopy at 30,000× and1,000,000× (FIGS. 6 and 8, respectively). The X-ray plot showed nodiscemable peak (similar to the results for Comparative Example 1,above). However, the optical micrograph and TEMs show greatly improvedplatelet particle separation as compared to Example 1. FIGS. 4, 6 and 8clearly show much better dispersion of the platelet particles and farfewer large agglomerates than the micrographs for the plateletparticle-polyester composite which was not treated with an water solublepolymer (Comparative Example 1). Thus, the compositions of the presentinvention display much better dispersion as compared to those without awater soluble polymer. Moreover, it is clear that X-ray data alone isinsufficient to confirm the degree of separation of the plateletparticles in the selected polyester. The film made from the Example 1material was tested for oxygen permeability and, consistent with theimproved dispersion, was found to exhibit improved barrier relative toneat PET (Comparative Example 1).

It should be noted that the micrographs included herewith are believedto representative. Because of the small area represented by anymicrograph other areas displaying differing levels of dispersion in agiven sample are likely to exist. The areas selected are believed to berepresentative of average morphology of the reported samples.

Comparative Example 2 Polymer Intercalated Montmorillonite With AQ 55

PET pellets (9921, Eastman Chemical Company) were placed in a convectionoven at 110° C. until processed (minimum of twelve hours, maximum oftwenty-four hours) by extrusion compounding. The pellets weretumbled-mixed with PVP-intercalated Montmorillonite clay (30 parts PVPto 70 parts clay; twenty grams total silicate by weight, NanomerPVP-BPW, from Nanocor, Inc.) that had been spray dried to a fine powderand melted-blended using a Micro-18 compounding twin screw compoundingextruder, with a high shear/mixing screw, obtaining pellets as theproduct. The run conditions were set at 240° C. for the first screwheating zone and 280° C. for heating zones two through eight. The RPM ofthe extrusion screw was maintained at 200 plus or minus five rpm. Theproduct feed screw was set to maintain 2.5 kg/hr. The molten strand wasquenched in chilled water and chopped immediately thereafter. Thepellets were dried at 100° C. over night in a force air drier andextruded into film. The compounded pellets were analyzed by OpticalMiscroscopy (FIG. 9) which showed large agglomerates of poorly spacedplatelet particles indicating poor dispersion. The oxygen permeabilityof the film showed no substantial improvement, confirming the poordispersion of platelet particles.

Example 2 Polymer Intercalated Montmorillonite With AQ 55

An AQ 55 dispersion was made, such that, every 100 grams of dispersioncontained thirty grams AQ 55 total solids by weight and seventy gramsMillipore water by weight, giving a total solids in the dispersion equalto 30% by weight. A "slurry" of Millipore water and clay that had beenintercalated with Polyvinylpyrollidone (PVP) (30 wt % intercalantpolymer to clay, Nanomer PVP-BPW, from Nanocor, Inc) and spray dried toa fine powder, was made by adding twenty grams (total silicate byweight) of intercalated Montmorillonite to 600 grams of Millipore water.The clay was dispersed with a three-blade mixer until the clay appearedto be fully wet. At this point an Ultra-Turrax 25 with the S25n-25Fdispersing tool was used to input high shear mixing (18,000 rpm) for twominutes. After high shear mixing of the slurry, 266.7 grams of EastmanChemical Company AQ55 30% dispersion was added to the slurry. Using theUltra-Turrax 25 the water/AQ 55/clay/PVP dispersion was sheared for anadditional five minutes. PET pellets (9921W, Eastman Chemical Company),1680 grams, were placed in a Sigma Mixer that had been preheated to aminimum of 85° C. The water/AQ55/clay slurry was poured over the pelletsand mixed in the Sigma Blade mixer until the water from the dispersionhad evaporated. A flow of a minimum of twenty cubic feet per hour ofheated nitrogen was released over the pellets to help evacuate thewater.

The coated pellets were placed in a convection oven at 110° C. untilprocessed (minimum of twelve hours, maximum of twenty-four hours) byextrusion compounding. The coated pellets were extruded using a Micro-18twin screw compounding extruder, with a high shear/mixing screw,obtaining pellets as the product. The run conditions were set at 240° C.for the first screw heating zone and 280° C. for heating zones twothrough eight. The RPM of the extrusion screw was maintained at 200 plusor minus five rpm. The product feed screw was set to maintain 2.5 kg/hr.The molten strand was quenched in chilled water and chopped immediatelythereafter. The pellets were dried at 100° C. over night in a force airdrier and extruded into film. The compounded pellets were analyzed byOptical Miscroscopy at 20× (FIG. 10) and found to exhibit improveddispersion as compared to Comparative Example 2 (FIG. 9).

Comparative Example 3 Quaternary Ammonium Modified MontmorilloniteWithout AQ 55

PET pellets (9921, Eastman Chemical Company) were placed in a convectionoven at 110° C. until processed (minimum of twelve hours, maximum oftwenty-four hours) by extrusion compounding. The pellets weretumble-mixed with quarternary ammonium modified Montmorillonite(Claytone APA supplied by Southern Clay Products, 2 wt % silicate to PETmatrix) and then melt-blended using a Micro-18 twin screw compoundingextruder, with a high shear/mixing screw, obtaining pellets as theproduct. The run conditions were set at 240° C. for the first screwheating zone and 280° C. for heating zones two through eight. The RPM ofthe extrusion screw was maintained at 200 plus or minus five rpm. Theproduct feed screw was set to maintain 2.5 kg/hr. The molten strand wasquenched in chilled water and chopped immediately thereafter. Thepellets were dried at 100° C. over night in a force air drier andextruded into film. The film was analyzed by Optical Miscroscopy at 20×(FIG. 11) and Transmission Electron Miscroscopy at 100,000×, (FIG. 13)and tested for oxygen permeability. Consistent with the other examplesof untreated clay materials, the film of Comparative Example 3 showedrelatively poor platelet particle dispersion, with many largeagglomerates containing closely spaced platelet particles. Very fewindividual particles or tactoids were observed.

Example 3 Quaternary Ammonium Modified Montmorillonite With AQ 55

An AQ 55 dispersion was made, such that, every 100 grams of dispersioncontained thirty grams AQ 55 total solids by weight and seventy gramsMillipore water by weight, giving a total solids in the dispersion equalto 30% by weight. A "slurry" of Millipore water and clay was made byadding forty grams (total silicate by weight) of quarternary modifiedMontmorillonite (Claytone APA supplied by Southern Clay Products) thathad been surface modified using a H-tallow, benzyl, dimethyl ammoniumchloride to 600 grams of Millipore water. The clay was dispersed with athree-blade mixer until the clay appeared to be fully wet. At this pointan Ultra-Turrax 25 with the S25n-25F dispersing tool was used to inputhigh shear mixing (18,000 rpm) for two minutes. After high shear mixingof the slurry, 266.7 grams of Eastman Chemical Company AQ55 30%dispersion was added to the slurry. Using the Ultra-Turrax 25 thewater/AQ 55/clay dispersion was sheared for an additional five minutes.PET pellets (9921, Eastman Chemical Company), 1680 grams, were placed ina Sigma Blade Mixer that had been preheated to a minimum of 85° C. Thewater/AQ55/clay slurry was poured over the pellets and the newdispersion was mixed in the Sigma Blade mixer until the water from thedispersion had evaporated. A flow of a minimum of twenty cubic feet perhour of heated nitrogen was released over the pellets to help evacuatethe water.

The coated pellets were placed in a convection oven at 110° C. untilprocessed (minimum of twelve hours, maximum of twenty-four hours) byextrusion compounding. The coated pellets were extruded using a Micro-18twin screw compounding extruder, with a high shear/mixing screw,obtaining pellets as the product. The run conditions were set at 240° C.for the first screw heating zone and 280° C. for heating zones twothrough eight. The RPM of the extrusion screw was maintained at 200 plusor minus five rpm. The product feed screw was set to maintain 2.5 kg/hr.The molten strand was quenched in chilled water and chopped immediatelythereafter. The pellets were dried at 100° C. over night in a force airdrier and extruded into film. The compounded pellets were analyzed byOptical Miscroscopy at 20× and Transmission Electron Microscopy at100,000×. Both levels of magnification show very good dispersion withonly tactoids and individual platelet particles present, indicating gooddispersion.

Comparative Example 4 and Examples 4-8

An AQ 55 dispersion was made, such that, every 100 grams of dispersioncontained thirty grams AQ 55 total solids by weight and seventy gramsMillipore water by weight, giving a total solids in the dispersion equalto 30% by weight. A "slurry" of Millipore water and clay was made byadding forty grams (total silicate by weight) of Sodium Montmorillonitefrom Southern Clay Products to 600 grams of Millipore water. The claywas dispersed with a three-blade mixer until the clay appeared to befully wet. At this point an Ultra-Turrax 25 with the S25n-25F dispersingtool was used to input high shear mixing (18,000 rpm) for two minutes.After high shear mixing of the slurry, 0, 133.5, 266.7, 533.4, and 933.4grams of Eastman Chemical Company AQ55 30% dispersion was added to the.Using the Ultra-Turrax 25 the water/AQ 55/clay dispersion was shearedfor an additional five minutes. PET pellets (9921, Eastman ChemicalCompany), 1680 grams, were placed in a Sigma Blade Mixer that had beenpreheated to a minimum of 85° C. The water/AQ55/clay slurry was pouredover the pellets and the new dispersion was mixed in the Sigma Blademixer until the water from the dispersion had evaporated. Pellets werecoated to four concentration levels, 2, 4, 8 and 14 wt % AQ-55 (Examples4-8, respectively). A flow of a minimum of twenty cubic feet per hour ofheated nitrogen was released over the pellets to help evacuate thewater. The coated pellets were placed in a convection oven at 110° C.until processed (minimum of twelve hours, maximum of twenty-four hours)by extrusion compounding using a Leistritz Micro-18 twin screw meltcompounding extruder. The run conditions were set at 240° C. for thefirst screw heating zone and 280° C. for heating zones two througheight. The RPM of the extrusion screw was maintained at 200 plus orminus five rpm. The molten strand was quenched in chilled water andchopped immediately thereafter.

Comparing the Transmission Electron Micrographs (TEMs) of the foursamples containing increasing loading of water dispersible polymer(FIGS. 14-17) to the unmodified PET (FIG. 13), the positive affect ofthe water dispersible polymer on platelet particle dispersion in PET isdemonstrated. The PET-platelet particle composite without waterdispersible polymer contains mostly very large aggregates as shown inFIG. 13. As water dispersible polymer is added in amounts increasingfrom 2 to 8 weight % the clay aggregates become much smaller and moreswollen with polymer as shown by FIGS. 14 through 17 respectively. Atabout 14 weight % water dispersible polymer the composite showsexcellent separation, with predominantly individual platelet particlesand a few small tactoids. The dispersion shown in FIG. 17 provides apolyester-platelet particle composite with 56% lower oxygen permeabilityrelative to unmodified PET. This result was totally unexpected. Whilethe amount of water dispersible polymer effects the degree of plateletseparation achieved, other factors such as type of clay and otheradditives which are used are also important.

We claim:
 1. A process comprising the steps of dispersing a chalcogen or at least one clay material in a water dissipatible polymer to form a platelet particle dispersion; introducing said dispersion to a polyester and extrusion mixing said dispersion and polyester to form a platelet particle-polyester composite composition wherein said platelet particles primarily comprise platelet particles and tactoids.
 2. The process of claim 1 wherein said composite composition has a gas permeability which is at least 5% lower than that of unmodified polyester.
 3. The process of claim 1 wherein said platelet particle is present in an amount between about 0.01 weight % and about 25 weight %.
 4. The process of claim 1 wherein said platelet particle is present in an amount between between about 0.5 weight % and 25 weight %.
 5. The process of claim 1 wherein said platelet particle is present in an amount between about 0.5 and about 15 weight %.
 6. The process of claim 1 wherein said platelet particle is present in an amount between about 0.5 weight % and 10 weight %.
 7. The process of claim 1 wherein said platelet particles have a thickness of less than about 2 nm and a diameter in the range of about 10 to about 1000 nm.
 8. The process of claim 1 wherein said water dissipatible polymer has an inherent viscosity of at least about 0.1 dL/g.
 9. The process of claim 1 wherein said water dissipatible polymer is selected from the group consisting of sulfonate-containing, water-dispersible, linear polyesters and polyester-amides.
 10. The process of claim 9 wherein said polyester or polyester-amide comprises residues of (1) one or more dicarboxylic acids and (2) one or more diols or a combination of one or more diols and one or more diamines.
 11. The process of claim 9 wherein said water dissipatible polymer further comprises residues of monomers having both acid and hydroxy functionality.
 12. The process of claim 10 wherein said residues are derived from monomer components selected from the group consisting of dicarboxylic acid, dialkyl esters, bis(hydroxyalkyl)esters, acid chlorides, anhydrides hydroxycarboxylic acid, aminocarboxylic acid, aminoalcohol, glycol, diamine and combinations thereof wherein at least a part of the total of all such monomer components is poly(ethylene glycol), and at least a part of said total is one or more of said monomer components substituted with one or more sulfonate metal salt groups.
 13. The process of claim 12 wherein said sulfonate group is selected from the group consisting of alkali metal sulfonic salts and substituted or unsubstituted ammonium sulfonate.
 14. The process of claim 13 wherein said sulfonate group is an alkali metal sulfonic salt selected from the group consisting of lithium, potassium and sodium sulfonate groups.
 15. The process of claim 1 wherein said water dissipatible polymer has an inherent viscosity of about 0.28 to 0.38 dL/g and is comprised of:(i) diacid monomer residues comprising about 75 to 84 mole percent isophthalic acid monomer residues and about 16 to 25 mole percent 5-sodio-sulfo-isophthalic acid monomer residues; and (ii) diol monomer residues comprising about 45 to 60 mole percent diethylene glycol monomer residues and about 40 to 55 mole percent ethylene glycol, 1,4-cyclohexanedimethanol monomer residues or mixtures thereof.
 16. The process of claim 1 wherein said water dissipatible polymer is present in an amount which is at least about 1 part water dissipatible polymer to 1 part said polyester.
 17. The process of claim 1 wherein said water dissipatible polymer is present in an amount which is between about 1 and about 20 parts water dissipatible polymer to 1 part said polyester.
 18. The process of claim 1 wherein said water dissipatible polymer is present in an amount which is between about 1 and about 15 parts water dissipatible polymer to 1 part said polyester.
 19. The process of claim 1 wherein said water dissipatible polymer is present in an amount which is between about 1 and about 10 parts water dissipatible polymer to 1 part said polyester.
 20. The process of claim 1 wherein the introducing step is accomplished via (1) wet coating the dispersion onto polyester pellets, or (2) drying the dispersion and introducing the dried dispersion onto or into polyester pellets.
 21. A process for preparing a polyester composite material comprising the steps of:(i) introducing a clay material into water to form an aqueous clay/water suspension; (ii) dispersing the clay/water suspension in a water dissipatible polymer to form a platelet particle slurry dispersion; (iii) introducing the slurry dispersion to a polyester; (iv) removing water from the slurry dispersion and polyester to coat the polyester with the water dissipatible polymer and platelet particles; and (v) extrusion mixing the polyester to form a platelet particle-polyester composite composition wherein the platelet particles primarily comprise platelet particles and tactoids.
 22. The process of claim 21 wherein the composite composition has a gas permeability which is at least 5% lower than that of unmodified polyester.
 23. The process of claim 21 wherein the platelet particle is present in an amount between 0.5 weight % and 25 weight %.
 24. The process of claim 21 wherein the platelet particle is present in an amount between 0.5 and 15 weight %.
 25. The process of claim 21 wherein the platelet particle is present in an amount between 0.5 weight % and 10 weight %.
 26. The process of claim 21 wherein the platelet particles have a thickness of less than about 2 nm and a diameter in the range of about 10 to about 1000 nm.
 27. The process of claim 21 wherein the water dissipatible polymer is selected from the group consisting of water-dissipatible meltable polyesters and polyesteraides.
 28. The process of claim 29 wherein the polyesters and polyesteramides are derived from monomer components selected from the group consisting of dicarboxylic acid, hydroxycarboxylic acid, aminocarboxylic acid, aminoalcohol, glycol, diamine or combinations thereof wherein at least a part of the total of all such monomer components is poly(ethylene glycol), and at least a part of the total is one or more of the monomer components substituted with one or more sulfonate metal salt groups. 